Research On The Miniaturization Of Circularly Polarized Antennas

Circularly polarized antennas play an irreplaceable role in the field of wireless communications as it can receive any kind of polarized wave and has strong adaptability to complex and varied application environments.With the rapid development of communication systems,communication equipment has also become increasingly miniaturized.In order to adapt to its development trend,miniaturization of circularly polarized antennas has always been a focus of attention.Based on this research background,this paper systematically studies the miniaturization of circularly polarized antennas and focuses on the miniaturization of quadrifilar helical antenna and monopole array circularly polarized antenna,and two types of antennas with good circular polarization performance are designed in this paper.Firstly,a small printed quadrifilar helical antenna combined with a self-phase shifting technology and a flexible PCB is designed.The spiral arm is designed using a self-phase shift technique to produce a 90ophase difference,which reduces the complexity of the feed network design.The printed network is printed on a flexible PCB and is conformal to the antenna radiating element to reduce the overall transverse dimension(ie width)of the antenna,so that the antenna structure is compact.The measuered results show that the antenna has a maximum gain of 3.5 dBi and a beam width of 170°.On this basis,by folding the spiral arms of the four-arm spiral,the longitudinal size(ie height)of the antenna is reduced,and the miniaturized design of the antenna is further realized.The overall size of the antenna is only 40mm×20mm.The overall antenna size is only40mm×20mm,the height is reduced by about 30%compared with the previous,and the simulation gain is 3.9 dBi at maximum,and the beam width is 170°,which meets the requirements of GPS communication systems.Secondly,a low profile circularly polarized antenna based on the printed monopole and sequential rotation technology is designed.The antenna consists of six printed monopoles and a feed network with a sequential rotation structure.By reducing the monopole in the plane of the dielectric plate and the space plane at the same time,the size of the antenna is reduced,especially in terms of height.Sequential rotation technology is used to array six monopole elements and use a combination of a microstrip feed network and a phase shifter to achieve unit feed amplitude and phase requirements in a small space and achieve good circular polarization radiation performance.The results of processing and testing of the antenna show that the designed antenna has good circular polarization performance and a small size.The antenna operates at a center frequency of 1.575GHz and it's overall size is only 50mm×7mm,the maximum gain is 2dBi,and the beam width is 140°.